The Last Pages of Theexam Are Reference Tables

Chemistry 106: General Chemistry

Syracuse University Project Advance

Exam #3, Fall 2006

NameDate

The last pages of theexam are reference tables.

1)The molecule POCl3 has bonding that is similar to that of the phosphorus atoms in almost all biological molecules. Write the Lewis structure for POCl3, assuming P is in the center of the molecule, with the requirement that every atom gets an octet of electrons. The formal charge on P is:

a)-2

b)-1

c)0

d)+1

e)+2

2)Write a Lewis formula for the nitrite ion, NO2-. Make sure that the octet rule is followed. What is the total number of bonds in your formula? (A double bond counts as two bonds, a triple bond counts as three)

a)1

b)2

c)3

d)4

e)5

3)From a consideration of the Lewis structure of the thiocynate ion SCN-, in which carbon has a double bond with both the sulfur and nitrogen atoms, the formal charges on the sulfur, carbon, and nitrogen atoms are, respectively,

a)-2, +1, 0

b)0, 0, -1

c)-2, 0, +1

d)-1, 0, 0

e)-1, +1, -1

4)Which of the following has a Lewis structure most like that of NO-?

a)NO+

b)O22-

c)O2-

d)O2

e)NO

5)A bond in which an electron is unequally shared by two atoms is

a)coordinate covalent

b)dipolar

c)polar covalent

d)nonpolar covalent

e)ionic

6)In the Lewis structure of ClF3, the number of lone pairs of electrons around the central atom is

a)0

b)1

c)2

d)3

e)4

7)Which of the following statements about resonance is/are correct?

I. When resonance exists, a single Lewis structure does not adequately represent the bonding.

II. Resonance describes a more stable situation than does any one contributing structure.

III. When resonance exists, the formal charges on all the atoms in the molecule are equal to zero.

a)I and II

b)II and III

c)I and III

d)All are correct

e)None are correct

8)Write the Lewis electron-dot formula for CO2 and use it to predict the shape or geometry of this molecule using the VSEPR model.

a)Bent (angular)

b)Linear

c)Tetrahedral

d)Trigonal Planar

e)Trigonal Pyramidal

9)Which of the following is/are correct?

I. The core electronic configuration of the ground state of the cobalt atom is 1s22s22p63s23p6.

II. The valence shell electronic configuration of the ground state of the bromine atom is 4s24p5.

III. The complete ground state electronic configuration of the manganese atom is 1s22s22p63s23p63d54s2.

a)I and II

b)I and III

c)II and III

d)All are correct

e)None are correct

10)Write the Lewis electron-dot formula for NF3 and use it to predict the shape or geometry of this molecule using the VSEPR model.

a)Bent (angular)

b)Tetrahedral

c)Trigonal Planar

d)Trigonal Pyramidal

e)Linear

11) What hybrid orbitals of sulfur are involved in the bonding in sulfur trioxide?

a)sp

b)sp2

c)sp3

d)dsp3

e)d2sp3

12)Which of the following species has a bond order of 2.5?

a)NO-

b)O22-

c)O2-

d)O2

e)O2+

13)According to the VSEPR model, the molecule COF2 (C in the middle) is:

a)linear

b)square planar

c)pyramidal

d)trigonal planar

e)zig-zag

14)The nitrosyl ion, NO+, has ten bonding electrons and four antibonding electons. Therefore, it has a bond order of

a)5/2

b)1

c)2

d)7

e)3

15) In the ICl4- ion, the electron pairs are arranged around the central iodine in the shape of

a)an octahedron

b)a tetrahedron

c)a trigonal bipyramid

d)a trigonal pyramid

e)a square plane

16) Which of the following molecules has/have sp3 hybrid orbital on the central atom(s)?

I. CH4

II. BF3

III. H2O

IV. H2C=CH2

V. NH3

a)II and IV

b)I and III

c)I, II and V

d)I, II and III

e)I, III and V

17) A  (pi) bond is the result of:

a)overlap of twp sp2 hybrid orbitals

b)overlap of two p orbitals along their axes

c)sidewise overlap of two parallel p orbitals

d)overlap of two s orbitals

e)overlap of an s and a p orbital

18) An ionic bond involves overlapping orbitals of the ions that compose it.

a)true

b)false

c)depends upon the compound.

19) Which of the following does not describe a covalent bond.

a)a bond which involves overlapping orbitals of the atoms that compose it.

b)a bond in which the electrons are attracted simultaneously to both positive nuclei forming the bond.

c)a bond between a 1s orbital on hydrogen and a singly-occupied 2p orbital on fluorine.

d)a bond symbolized by the line in H-Br.

e)a bond in the chlorine molecule, Cl2, formed by sharing of the 1s orbitals on each of the chlorine atoms.

20)The density of a gas is 3.48 g/L at STP. What is its molecular weight?

a)44.6 g/L

b)224 g/L

c)78.0 g/L

d)32.0 g/L

e)147 g/L

21) A given mass of a gas occupies a volume of 4.00 L at 60° C and 550 mm Hg. Which of the following mathematical expressions will yield its pressure at 3.00 L and 30° C?

a)

b)

c)

d)

e)

22)We collected 20.0 L of CO2 at a pressure of 1 atm, T = 23° C. What is the volume of the gas if T is increased to 30° C?

a)15.3 L

b)19.5 L

c)20.0 L

d)20.5 L

e)26.1 L

23)20.0 L of CO2 is contained in a tank at 23° C and 1.00 atm pressure. Gas is allowed to escape from the tank slowly (keeping the temperature constant) until the pressure drops to 0.50 atm. How many moles of gas are left in the tank?

a)0.000873 mol

b)0.00175 mol

c)0.411 mol

d)0.823 mol

e)0.870 mol

24)Real gases deviate from the ideal gas law at high pressures because

a)the pressure causes the paths of the molecules to deviate from straight lines.

b)the gas becomes non-uniform due to convection currents

c)increasing the pressure makes the temperature increase.

d)molecules react with each other to form larger molecules

e)the molecules get close enough together so that intermolecular forces are important.

25)Two 3.0 L sealed flasks, each at a pressure of 940 mmHg are in a room. One contains He and the other Ar. If the flask containing Ar is heated:

a)then the flask containing Ar would be at a lower pressure than the flask containing He.

b)then the flask containing Ar would be at a higher pressure than the flask containing He.

c)there is insufficient information to draw a conclusion about the relative pressures of the two flask.

d)the two flasks would be at the same pressure.

e)None of the above.

26)A sample of oxygen gas occupies a volume of 900 mL at a pressure of 100 mmHg. What is the pressure of the gas if the volume is reduced to 300 mL and the temperature is doubled?

a)66.7 mmHg

b)33.3 mmHg

c)300 mmHg

d)150 mmHg

e)600 mmHg

27)If 4 mol of Neon gas and 6 mol of Krypton gas are contained in a flask whose total pressure is 1000 mmHg, the partial pressure of the Neon gas would be:

a)greater than the partial pressure of the Krypton gas.

b)less than the partial pressure of the Krypton gas.

c)same as the partial pressure of the Krypton gas.

EC) Ammonium Nitrite undergoes decomposition to produce only gases as shown below:

NH4NO2 (s)  N2 (g) + 2 H2O (g)

How many TOTAL liters of gas will be produced by the decomposition of 35.0 g of NH4NO2 (s) at 525oC and 1.5 atm? (SHOW ALL WORK)

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CHE 106 Fall Exam #3